API 602 Gate Valve: Complete Guide to Features, Specifications, and Applications

API 602 is the American Petroleum Institute standard that covers compact, bolted bonnet, forged steel gate valves for petroleum and natural gas industry applications. These valves are designed for NPS 1/4″ through NPS 4″ (DN 8 to DN 100) and pressure classes from 150LB to 2500LB. API 602 gate valves are distinguished by their forged steel construction, which provides superior strength, pressure integrity, and resistance to shock loads compared to cast steel alternatives.

Unlike the larger API 600 cast steel gate valves, API 602 valves are manufactured through forging processes that align the metal grain structure with the valve body contours, resulting in higher mechanical strength and better resistance to pressure-induced stresses. This makes them the preferred choice for critical service applications where reliability and safety are paramount.

Key Features of API 602 Gate Valves

1. Forged Steel Body Construction

The defining characteristic of API 602 gate valves is their forged steel body. Forging eliminates internal voids, porosity, and inclusions that can occur in castings. The forging process produces a dense, uniform grain structure that delivers superior mechanical properties including higher tensile strength, improved impact resistance, and better fatigue life. Available body materials include A105 (carbon steel), F304/F316 (stainless steel), F11/F22 (alloy steel), and F51 (duplex stainless steel) to match service requirements.

2. Bolted Bonnet Design

API 602 requires a bolted bonnet connection, which provides several advantages over welded or threaded bonnet designs. The bolted bonnet allows for easy in-line inspection, maintenance, and repair without removing the valve from the pipeline. This is especially important in critical services where downtime must be minimized. The bonnet gasket creates a reliable seal that can be replaced during routine maintenance.

3. Rising Stem and OS&Y Configuration

API 602 gate valves feature an Outside Screw and Yoke (OS&Y) design with a rising stem. The threaded stem is located outside the valve body and bonnet, preventing thread contact with the process fluid. This design provides visual position indication — a raised stem indicates an open valve. The OS&Y configuration also reduces wear on stem threads and packing, extending valve service life.

4. Full Port or Reduced Port Options

API 602 gate valves are available in both full port (full bore) and reduced port configurations. Full port valves have an internal diameter matching the pipe bore, minimizing pressure drop and allowing pig passage in pipeline applications. Reduced port valves have a smaller bore diameter that offers economic advantages in non-critical services where some pressure drop is acceptable.

5. Flexible Wedge or Solid Wedge Disc

The closure element of an API 602 gate valve can be either a flexible wedge or solid wedge disc. Flexible wedge discs are designed to compensate for variations in seating geometry caused by thermal expansion or piping loads, making them ideal for high-temperature and high-pressure applications. Solid wedge discs provide a simpler, more robust design suitable for moderate service conditions.

6. Renewable Seat Rings

API 602 standard calls for renewable or replaceable seat rings. These seat rings can be replaced when worn or damaged, extending the overall service life of the valve. Seat rings are typically made from corrosion-resistant materials and can be hard-faced with Stellite or other wear-resistant alloys for severe service applications.

API 602 Technical Specifications

Applications of API 602 Gate Valves

Oil and Gas Upstream

In upstream oil and gas operations, API 602 gate valves are used in wellhead equipment, flow lines, gathering systems, and manifold piping. The forged steel construction provides the integrity needed for high-pressure wellhead services where blowout prevention and leak-tight shutoff are critical. Sour service (NACE MR0175) trim options make them suitable for H₂S-containing environments.

Refinery and Petrochemical

Refineries rely on API 602 gate valves for process piping, catalyst handling, utility systems, and product transfer. The compact size of these valves (compared to API 600 valves) allows their use in tight piping arrangements common in refinery units.

Natural Gas Processing

Gas processing plants use API 602 gate valves in dehydration units, amine treatment systems, compressor stations, and pipeline metering facilities. Low-temperature carbon steel (ASTM A350 LF2) versions are available for cryogenic gas processing applications.

Power Generation

In thermal power plants, API 602 gate valves are employed in boiler feedwater systems, steam extraction lines, cooling water circuits, and fuel handling systems. Alloy steel versions (F11, F22) handle the high temperatures of superheated steam service.

Chemical Processing

The chemical industry uses API 602 gate valves for handling corrosive chemicals, acids, and caustic solutions. Stainless steel (F304, F316) and duplex stainless steel (F51) body materials provide corrosion resistance for aggressive chemical environments.

Offshore and Marine

Offshore platforms demand the highest integrity from their valve components. API 602 gate valves with corrosion-resistant trim, NACE compliance, and extended bonnet designs are standard in offshore production facilities.

API 602 vs API 600: Key Differences

For a more detailed comparison, see our API 600 vs API 602 Gate Valve: Complete Specification Guide.

API 602 Gate Valve FAQ

What is the difference between API 602 and API 600 gate valves?

API 602 covers compact, forged steel gate valves in sizes NPS 1/4″ to 4″, while API 600 covers cast steel gate valves in sizes NPS 2″ to 36″ and larger. API 602 valves are forged, providing superior strength and impact resistance, making them ideal for high-pressure small-bore applications. API 600 valves are cast and better suited for larger diameter mainline piping. See our detailed API 600 vs API 602 comparison guide for complete specifications.

What materials are available for API 602 gate valves?

API 602 gate valves are available in a range of forged materials including A105 (carbon steel) for standard service, F304/F316 (stainless steel) for corrosive environments, F11/F22 (alloy steel) for high-temperature applications, and F51/F53 (duplex stainless steel) for sour gas and aggressive chemical services. Trim materials range from 13Cr to Stellite hard-faced options per API Trim specifications.

What is the maximum pressure rating for API 602 gate valves?

API 602 gate valves are available in pressure classes up to 2500LB (Class 2500), which provides a maximum working pressure of up to 6,250 psi (431 bar) at ambient temperature, depending on the body material. Standard pressure classes include 150LB, 300LB, 600LB, 900LB, 1500LB, and 2500LB.

Can API 602 gate valves be used for sour gas service?

Yes, API 602 gate valves can be supplied with NACE MR0175/ISO 15156 compliant materials for sour gas (H₂S-containing) service. This requires specific material selections including hardness-controlled carbon steel bodies, corrosion-resistant trim materials, and appropriate heat treatment. Sour service valves must be clearly specified at the time of ordering.

What end connections are available for API 602 gate valves?

API 602 gate valves are available with threaded ends (NPT or BSPT), socket weld ends, butt weld ends, and flanged ends (RF or RTJ facing). The choice of end connection depends on the piping specification, pressure class, and service requirements. Socket weld and threaded ends are common for smaller sizes, while flanged connections are standard for larger sizes within the API 602 range.

Need an API 602 gate valve for your project? Contact Vornet Valve today for expert technical assistance and competitive pricing on forged steel gate valves.